Naslov
Shafting Alignment Calculation and Validation Criteria

Autori
Vulić, Nenad ; Šestan, Ante ; Cvitanić, Vedrana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Extended abstracts of the 5th International Congress of Croatian Society of Mechanics / Matejiček, Franjo - Zagreb : Hrvatsko društvo za mehaniku (HDM), 2006, 179-180

ISBN
953-96243-8-X

Skup
Međunarodni kongres Hrvatskog društva za mehaniku (5 ; 2006)

Mjesto i datum
Trogir, Hrvatska, 21.09.2006. - 26.09.2006

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
ship; propulsion; shaft line; alignment; transfer matrix method

Sažetak
The main propulsion shaft line, as the essential part of a modern ship propulsion system, is exposed to various operating conditions throughout the ships lifetime. Shaft line alignment procedure considers static and pseudo-static loading of the shafting in order to determine its static response. The main goal of this procedure is to determine and ensure achievement onboard the designed positions of the bearings in athwart direction in order to comply with certain criteria. The shaft line is usually modelled as a continuous multi-span beam on several supports. The supports may be considered as absolutely stiff, or linearly elastic, or even as real radial journal bearings. The paper describes the conventional shafting alignment calculation procedure and how to obtain and validate the designed situation onboard. Calculation presumptions, modelling of shafting parts, material properties and loading are given in detail. The important issue is to establish the designed shafting elastic line onboard the ship, during the outfitting phase in the shipyard. The validation procedure of the achieved shafting position is described, with a real life example. The shafting alignment calculation comprises the determination of support offsets, shafting elastic line and the determination of support reaction forces. In case of propulsion systems with gearboxes the scope of this analysis is restricted to shaft line from the propeller to the output shaft of the gearbox, together with its bearings and the bull gear. The data describing dimensions, material and loading of the shafts, as well as the bearings are to be available. The real system is modelled as a statically indeterminate system of variable section beams with multiple supports. Shaft line elements are modelled by means of circular section model elements. In general, the cross-section varies from one beam to another. The shaft line bearings are modelled by means of absolutely stiff or linearly elastic supports. Method of initial parameters in its matrix form (so called: transfer-matrix method) is chosen as the most appropriate modelling and calculation procedure. It is a pure analytical method which describes the whole system by smaller matrices than the finite element method. The calculation procedure has been implemented in the computer program MarShAl (Marine Shafting Alignment), specially developed for this purpose. For illustration a few characteristic diagrams obtained for an inland navigation ship are shown. Shaft line is to be properly aligned in order to ensure its proper functioning throughout the complete ship lifetime. Careful calculation, as well as setting up of its results onboard (for the ship afloat) and their validation during the assembly and testing phase is essential. From the authors’ experience it should be important to introduce the requirement for shafting alignment in the classification technical rules, even in the case of smaller ships. This will be the matter of further work.

Izvorni jezik
Engleski

Znanstvena područja
Brodogradnja, Strojarstvo

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